Communication system supporting transition between network communication protocols

ABSTRACT

This disclosure is directed to techniques for supporting transition between network communication protocols in a communication network. The techniques may be applicable to different network communication protocols, but are especially useful in the transition from the IPv4 communication protocol to the IPv6 communication protocol in a wireless communication network. In general, to reduce consumption of scarce IPv4 address during the transition period, a network communication device implementing a dual IPv4/IPv6 stack acquires an IPv4 address only when necessary to communicate with IPv4 resources on the network. The network communication device uses an IPv6 address at the start of a communication session, and does not acquire an IPv4 address unless a need arises later in the session for communication with an IPv4 resource. The IPv4 address may be acquired for a limited period of time, such as fixed period of time or a period of actual usage, to further promote availability of IPv4 addresses.

TECHNICAL FIELD

[0001] The disclosure relates to network communication and, moreparticularly, use of different network communication protocols within anetwork.

BACKGROUND

[0002] In a communication network, network nodes exchange data usingnetwork communication protocols. Internet Protocol (IP) is an example ofa network communication protocol that facilitates packetized datacommunication between network nodes. In an IPbased network, each networknode has an IP address. Existing networks generally use 32-bit IPaddresses according to IP Version 4 (IPv4). In particular, a packet sentbetween two network nodes generally includes a header with a source IPaddress and a destination IP address. The source address identifies thenode that sends the packet, and the destination address identifies theintended recipient of the packet.

[0003] Wireless communication networks conforming to the TIA IS-835standard, for example, rely on the IPv4 address space to identifywireless nodes ranging from network equipment to mobile wirelesscommunication devices. Dense mobile networks with millions ofindividually addressable nodes have resulted in rapid depletion of the32-bit address space provided by IPv4. With the limitations imposed bythe IPv4 address space, network carriers have contemplated a shift tothe 128-bit address space provided by IP Version 6 (Ipv6).

[0004] The transition from IPv4 to IPv6 presents some challenges. Forexample, a complete and sudden transition to IPv6 would disrupt accessto existing IPv4 resources on the network. The use of addresstranslation between IPv4 and IPv6 address spaces can ease thetransition, but generally presents undesirable processing overhead,expensive use of the air interface, and excessive power consumption.

[0005] The use of a so-called “dual stack” approach in which eachwireless communication device supports communication with either theIPv4 or IPv6 protocol is another solution for transition. During thetransition period, however, the typical dual stack implementationrequires assignment of both IPv4 and IPv6 addresses to the wirelesscommunication devices. The dual stack approach results in excessiveconsumption of IPv4 addresses, which is the precise reason thattransition to IPv6 addressing has been undertaken.

[0006] The IPv4 addresses can only be phased out after an extendedtransition period in which all or a large majority of the network nodeshave migrated to the IPv6 capabilities. In the meantime, the IPv4-IPv6transition remains a challenge, particularly for wireless communicationsystems providing mobile IP services.

SUMMARY

[0007] This disclosure is directed to techniques for supportingtransition between network communication protocols in a network. Thetechniques can be applied to different network communication protocols,but will be described in the context of transition from the IPv4communication protocol to the IPv6 communication protocol. In general,the techniques may be practiced in the context of a dual-stack networkcommunication device that supports both a first network communicationprotocol, e.g., IPv6, and a second network communication protocol, e.g.,IPv4. Although the techniques are applicable to both wired and wirelesscommunication devices, they may be especially useful in a mobilewireless communication network.

[0008] In general, to reduce consumption of scarce IPv4 addresses duringthe IPv4-IPv6 transition period, a mobile wireless communication deviceimplementing a dual IPv4/IPv6 stack acquires an IPv4 address only whennecessary to communicate with IPv4 resources on the network. Thewireless communication device uses an IPv6 address at the start of acommunication session, but does not obtain an IPv4 unless a need ariseslater in the communication session for communication with an IPv4network resource. In addition, the IPv4 address may be obtained for alimited period of time, such as fixed period of time or a period ofactual usage. Upon expiration of the period of time or termination ofactual usage, the mobile wireless communication device may release theIPv4 address to further promote availability of IPv4 addresses.

[0009] In an exemplary embodiment, this disclosure provides a methodcomprising automatically using a first address corresponding to a firstnetwork communication protocol for a mobile wireless communicationdevice upon commencement of a communication session, and selectivelyobtaining a second address corresponding to a second networkcommunication protocol for the mobile wireless communication device wheninitiating communication with a network resource that communicatesaccording to the second network protocol. The first networkcommunication protocol may be IPv6, and the second network communicationprotocol may be IPv4. In other embodiments, this disclosure provides adevice, wireless communication network and computer-readable mediumcapable of performing such a method.

[0010] In another embodiment, the disclosure provides a wirelesscommunication network comprising one or more first network nodes thatcommunicate according to a first network communication protocol, one ormore second network nodes that communicate according to a second networkcommunication protocol, a packet data serving node (PDSN) that providesaddresses corresponding to the second network communication protocol,and a mobile wireless communication device capable of communicatingaccording to the first network communication protocol and the secondnetwork communication protocol. The mobile wireless communication deviceautomatically uses an address corresponding to the first networkcommunication protocol upon commencement of a communication session, andselectively obtains an address corresponding to the second networkcommunication protocol when communication with a network resource thatcommunicates according to the second network protocol is necessary. Thefirst network communication protocol may be IPv6, and the second networkcommunication protocol may be IPv4.

[0011] In some cases, the techniques also may be applied tocommunication devices in wired networks. Accordingly, although thetechniques are generally described herein in the context of wirelesscommunication, application to wired communication devices is alsocontemplated. In those applications, the techniques may involveautomatically using a first address corresponding to a first networkcommunication protocol for a network communication device uponcommencement of a communication session, and selectively obtaining asecond address corresponding to a second network communication protocolfor the network communication device when initiating communication witha network resource that communicates according to the second networkprotocol.

[0012] The techniques described herein may be implemented in hardware,software, firmware, or any combination thereof. If implemented insoftware, the techniques may be directed to a computer readable mediumcomprising program code, that when executed, performs one or more of thetechniques described herein.

[0013] The details of one or more embodiments are set forth in theaccompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

[0014]FIG. 1 is a block diagram illustrating a wireless communicationnetwork.

[0015]FIG. 2 is a block diagram illustrating a mobile wirelesscommunication device (WCD).

[0016]FIG. 3 is a block diagram illustrating a packet date serving node(PDSN).

[0017]FIG. 4 is a flow diagram illustrating a technique for obtainingIPv4 addresses for use in a wireless communication network.

[0018]FIG. 5 is a flow diagram illustrating the technique of FIG. 4 infurther detail.

DETAILED DESCRIPTION

[0019]FIG. 1 is a block diagram illustrating a wireless communicationnetwork 10. As shown in FIG. 1, wireless communication network 10includes one or more network communication devices, such as mobilewireless communication devices (WCDs) 12A-12N (collectively mobile WCDs12). Mobile WCDs 12 communicate with a wireless network access point 14via a wireless communication channel. A packet data serving node (PDSN)16 is coupled between wireless access point 14 and an IP network 18,e.g., the Internet. Multiple IPv4 network nodes 20A-20N (collectivelyIPv4 nodes 20) and IPv6 network nodes 22A-22N (collectively IPv6 nodes22) communicate with PDSN 16 via IP network 18.

[0020] Mobile WCDs 12 send and receive data via the wirelesscommunication channel, and may take the form of cellularradiotelephones, satellite radiotelephones, PCMCIA cards incorporatedwithin portable computers, personal digital assistants (PDAs) equippedwith wireless communication capabilities, and the like. In addition,mobile WCDs 12 may include voice communication capabilities,particularly when embodied as a mobile handset. Mobile WCDs 12 mayemploy a variety of communication techniques, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), orfrequency division multiple access (FDMA), for communication over awireless communication channel. In some embodiments, the techniquesdescribed herein also may be applied to wired communication devices.

[0021] Wireless network access point 14 may take the form of a basestation antenna and controller equipped for data communication, voicecommunication, or both. PDSN 16 serves as a remote device for assignmentof IP addresses to mobile WCDs 12. In particular, PDSN 16 is responsiblefor assigning IP addresses to mobile WCDs 12, and establishing andsupporting IP traffic between the mobile WCDs and IP network 18. IPv4nodes 20 are capable of communicating according to the IPv4 networkcommunication protocol, and may take the form of a variety of networkresources such as web servers, database servers, web clients, I/Odevices, and the like. Similarly, IPv6 nodes 22 are capable ofcommunicating according to the IPv6 network communication protocol, andmay take forms similar to IPv4 nodes 20. PDSN 16 may be equipped to actas a foreign agent for mobile WCDs 12, handling care-of-addressing andnegotiation with home agents (not shown) coupled to IP network 18. Insome embodiments, the techniques described herein may be applied towired network servers that provide network addresses to networkcommunication devices.

[0022] For data communication, mobile WCDs 12 may take the form of dualstack devices that are capable of communication according to both afirst network communication protocol, e.g., IPv6, and a second networkcommunication protocol, e.g., IPv4. In other words, mobile WCDs 12implement both an IPv4 protocol stack and an IPv6 protocol stack, eachconfigured for mobile applications. In accordance with this disclosure,mobile WCDs 12 may be equipped to support transition between networkcommunication protocols within wireless communication network. Inparticular, mobile WCDs 12 may have one or more permanently assignedIPv6 addresses, and may be configured to obtain an IPv4 address onlywhen necessary to communicate with IPv4 resources within wirelesscommunication network 10, e.g., one of IPv4 nodes 20. In someapplications, the IPv6 addresses may be dynamically assigned to mobileWCDs 12.

[0023] Mobile WCDs 12 may be configured to use an IPv6 address from thestart of a communication session. For example, upon commencement of apoint-to-point protocol (PPP) session in a network 10 that supports bothIPv4 and IPv6, mobile WCD 12 may negotiate both Internet ProtocolControl Protocol (IPCP) and Internet Protocol Control Protocol version 6(IPCPv6). Mobile WCD 12 may determine that both IPv4 and IPv6 service isavailable within network 10 by detecting, e.g., upon powerup or thebeginning of a call, whether PDSN 16 transmits an IPCPv6 C-Req(configuration request).

[0024] Upon negotiating IPCP and IPCPv6, however, mobile WCD 12 isconfigured to not immediately request an IPv4 address from PDSN 16.Mobile WCD 12 does not request an IPv4 address unless an actual needarises in the course of the PPP session for communication with an IPv4resource, e.g., one of IPv4 nodes 20. Until that time, mobile WCD 12operates with an IPv6 address and communicates according to the IPv6network communication protocol. In this manner, IPv4 addresses can bemore effectively conserved within wireless communication network 10.

[0025] When mobile WCD 12 needs to communicate with an IPv4 node 20,i.e., when the mobile WCD needs to send the first IPv4 packet in the PPPsession, it requests an IPv4 address from PDSN 16. There are a varietyof ways in which mobile WCD 12 may obtain an IPv4 address in the courseof a PPP session. As one example, mobile WCD 12 may obtain the IPv4address by sending a mobile IP agent solicitation with a source IPaddress of 0.0.0.0. In response, PDSN 16 sends an agent advertisement.Upon receiving the agent advertisement, mobile WCD 12 sends aregistration request (RRQ) to PDSN 16. PDSN 16 forwards the registrationrequest to a home agent assigned to mobile WCD 12. The home agentassigns an IPv4 address to mobile WCD 12. PDSN 16 then sends aregistration reply (RRP) containing the IPv4 address to mobile WCD 12.In this manner, PDSN 16 provides mobile WCD 12 with the IPv4 address.From this point, mobile WCD 12 can communicate using IPv4, and therebyexchange packets with other IPv4 nodes 20 on IP network 18.

[0026] Obtaining the IPv4 address for mobile WCD 12 only when IPv4communication is actually needed conserves the number of available IPv4addresses within wireless communication network 10. Even though mobileWCD 12 may be a dual stack device, it does not consume an IPv4 addressunless IPv4 communication is needed. Instead, mobile WCD 12 implements a“selective” dual stack. Mobile WCD 12 initiates the PPP session with anIPv6 address automatically, and continues to communicate according toIPv6 until a request for communication with an IPv4 node 20 arises. Atthat time, mobile WCD 12 may selectively request an IPv4 address. Inaddition to conserving IPv4 addresses, in some embodiments, theselective dual stack arrangement can avoid the need for IPv4-IPv6address translation, and the associated processing overhead, airinterface usage and power consumption.

[0027] To further promote conservation of IPv4 addresses, mobile WCD 12,PDSN 16, or both may be configured to release or withdraw, respectively,an IPv4 address in response to expiration of a period of time, e.g., alimited IP lease time, or in response to termination of a communicationwith an IPv4 node 20. In other words, in some exemplary embodiments, theIPv4 address, once assigned, may be retained for either a limited periodof time or the time during which IPv4 communication is actually needed.

[0028] The period of time for retention of the IPv4 address may be afixed period of time that is predetermined for all mobile WCDs 12.Alternatively, the period of time may vary, e.g., based on the level ofconsumption of IPv4 addresses within wireless communication network 10.Also, it may be desirable to set the period of time on a per-user basis,so that legacy mobile WCDs 12 having only IPv4 communicationcapabilities are not given exceedingly short lease times. To distinguishdual stack mobile WCDs 12 from IPv4-only mobile WCDs, the dual stackmobile WCDs may be configured to request shorter lease times inregistration requests. In each case, PDSN 16, or alternatively the homeagent for the mobile WCD or an applicable Authentication, Authorizationand Accounting (AAA) server, may be responsible for determining theperiod of time applicable to IPv4 addresses. However, either PDSN 16 ormobile WCD 12 or both may be configured to track the period of time andexpiration.

[0029] Upon expiration of the period of time or completion ofcommunication between mobile WCD 12 and an IPv4 node 20, PDSN 16 maysend a termination notification to mobile WCD 12. The terminationnotification may advise mobile WCD 12 that the present IPv4 address hasexpired and will no longer be valid within wireless communicationnetwork 12. Alternatively, the termination notification may be generatedinternally by mobile WCD 12 in the event the mobile WCD tracksexpiration of the least time or completion of communication. Mobile WCD12 may respond by releasing the IPv4 address, and can be configured tonot immediately reregister following release of the IPv4 address unlessa new IPv4 communication is required. As a result, a single mobile WCD12 retains an IPv4 address for only a fixed period of time, which may bedetermined by PDSN 16 and, ultimately, the network carrier.

[0030] In some embodiments, PDSN 16 may be configured to mandate releaseof an IPv4 address upon consent by mobile WCD 12. In this case, iffurther IPv4 communication is anticipated, mobile WCD 12 may bepermitted to retain the IPv4 address for a limited period of time.Alternatively, PDSN 16 may simply invalidate the IPv4 addressunilaterally, in which case further IPv4 communications by mobile WCD 12will be ineffective. Also, if PDSN 16 invalidates the IPv4 address andmobile WCD 12 received the address through Mobile IP, the PDSN can alsoadvise the home agent for the mobile WCD that the pertinent IPv4 addresshas been released and that the home agent is free to assign the addressto some other device. In either case, if the IPv4 address is released,to commence further IPv4 communication, mobile WCD 12 may restart theregistration process with PDSN 16 to obtain another IPv4 address.

[0031] If wireless communication network 10 is a Simple IPv4 network,when mobile wireless communication device 12 determines that both IPv4and IPv6 service are available, it may be configured to negotiate IPCPv6without negotiating IPCPv4 upon initiation of a PPP session. Notably, insome other wireless networks, in which PPP is not used, there may beother modes for obtaining an IPv4 address. When mobile wirelesscommunication device 12 needs to send or receive an IPv4 packet, itsends an IPCP C-Req and, in reply, receives an IPv4 address from PDSN16. Mobile wireless communication device 12 thereafter engages in IPv4communication subject to possible lease time or usage limitations asdescribed herein.

[0032] If PDSN 16 begins to exhaust its supply of IPv4 addresses, it canbegin to withdraw the addresses from mobile WCDs 12 on a proactivebasis, e.g., by sending an IPCP T-Req (termination request) to selectedmobile WCDs. PDSN 16 may undertake this operation when IPv4 addressesare scarce even if applicable lease time periods have not expired. Forexample, PDSN 16 may track mobile WCDs 12 that have not received or sentIPv4 traffic for an extended period of time, and withdraw addresses fromthose mobile WCDs first.

[0033]FIG. 2 is a block diagram illustrating an exemplary mobile WCD 12that may be used in wireless communication network 10 of FIG. 1. Asshown in FIG. 2, mobile WCD 12 may include a processor 28, modem 30,radio circuit 32, antenna 34, and memory 35. Memory 35, which may takethe form of FLASH, ROM, or the like, stores code executed by processor28 to implement a dual protocol stack. In particular, processor 28implements a dual protocol stack, represented by IPv4 stack 36 and IPv6stack 38, to send and receive IP-based packets. Modem 30 modulates anddemodulates packets transmitted and received via radio circuitry 32 andantenna 34.

[0034] Processor 28 automatically uses an IPv6 address for wirelesscommunication upon commencement of a communication session, e.g., a PPPsession. The IPv6 address may be permanently or dynamically assigned toprocessor 28. In addition, mobile WCD 12 may have multiple IPv6addresses. Processor 28 selectively obtains an IPv4 address, however,when communication with a network resource that communicates accordingto IPv4 is necessary.

[0035] As described with reference to FIG. 1, processor 28 may beconfigured to retain the IPv4 address for a period of time, e.g., alease time, or for the duration of a communication session with an IPv4node 20. Upon expiration of the period of time or detection ofcompletion of the communication session, or upon determination that allIPv4 communication applications have finished, processor 28 may releasethe IPv4 address, permitting it to be reassigned by PDSN 16.Alternatively, processor 28 may release the IPv4 address in response toa termination notification sent by PDSN 16 in the event the PDSN trackslease time or usage time.

[0036]FIG. 3 is a block diagram illustrating a PDSN 16 that may be usedin wireless communication network 10 of FIG. 1. As shown in FIG. 3, PDSN16 may include a processor 40, a network interface 42, and memory 43storing instructions for execution by processor 40. PDSN 16 isconfigured to handle PPP negotiation, including IPCPv4 and IPCPv6processes 44, 46, respectively. In particular, PDSN 16 may serve as aforeign agent for mobile WCDs 12 that enter an area served by accesspoint 14 and PDSN 16, and provide IPCP and mobile IP registrationservices. Also, when Mobile IPv4 is used, PDSN 16 acts as the foreignagent. As further shown in FIG. 3, PDSN 16 executes IPv4 and IPv6network protocol stacks 45, 47.

[0037] In addition, in the course of IPCP or registration, PDSN 16provides IPv4 addresses to mobile WCDs 12 that request them. In thismanner, PDSN 16 supports a technique for assignment of IPv4 address onan as-needed basis, thereby conserving IPv4 addresses. Once an IPv4address has been assigned, PDSN 16 may assign a lease period and monitorelapsed time. Upon expiration of the lease period, PDSN 16 may send atermination notification to a mobile WCD 12 to request that the IPv4address be released. Alternatively, PDSN 16 may unilaterally withdrawthe IPv4 address from a mobile WCD 12 upon expiration of the lease time.

[0038] As a further alternative, PDSN 16 may monitor IPv4 traffic to andfrom mobile WCD 12 and detect a period of inactivity, i.e., a period inwhich no IPv4 traffic is transmitted to or sent by the mobile WCD 12. Inthis case, PDSN 16 may withdraw the IPv4 address or send a terminationnotification to mobile WCD 12, requesting release of the IPv4 address.

[0039]FIG. 4 is a flow diagram illustrating a technique for obtainingIPv4 addresses for use in wireless communication network 10. As shown inFIG. 4, when a mobile WCD 12 initiates a network communication session(48), it automatically retrieves an IPv6 address (50) from local memoryfor use in the communication session. In this example, the IPv6 addressis permanently assigned to mobile WCD 12. In other cases, the IPv6address may be dynamically assigned, e.g., upon interaction with PDSN16. Thereafter, mobile WCD 12 communicates via the IPv6 stack (52) withIPv6 nodes on network 10.

[0040] When IPv4 communication is needed (54), mobile WCD 12 requests anIPv4 address (56) from PDSN 16. Upon assignment of the IPv4 address andan IPv4 lease time (58), mobile WCD 12 communicates via the IPv4 stack(60), e.g., concurrently with the IPv6 stack. In other words, uponassignment of the IPv4 address, mobile WCD 12 may communicate usingeither the IPv4 stack or the IPv6 stack. When the IPv4 lease timeexpires (62), mobile WCD 12 releases the IPv4 address (64).Alternatively, if the IPv4 lease time has not expired, but the IPv4communication has terminated (66), mobile WCD 12 likewise releases theIPv4 address (64).

[0041]FIG. 5 is a flow diagram illustrating the technique of FIG. 4 infurther detail. As shown in FIG. 5, when a mobile WCD 12 initiates acommunication session (66), mobile WCD 12 may first determine whetherIPv4 service is supported within the service area in which the mobileWCD 12 presently resides (68). In other words, mobile WCD 12 determineswhether the network equipment, e.g., PDSN 16, supports IPv4 service. Ifnot, mobile WCD 12 negotiates IPCPv6 only (70) and retrieves the IPv6address assigned to the mobile WCD (72). Thereafter, mobile WCD 12communicates via the IPv6 stack only (74). If IPv4 service is available,however, mobile WCD 12 negotiates both IPCPv4 and IPCPv6 (76) with PDSN16, but does not immediately request an IPv4 address. Instead, mobileWCD 12 initially retrieves the IPv6 address (78) and communicates viathe IPv6 stack (80).

[0042] When IPv4 communication is needed (82), mobile WCD 12 requests anIPv4 address from PDSN 16 by sending an IPv4 agent solicitation (84). Inresponse, mobile WCD 12 receives an agent advertisement (86) from PDSN16, and then sends a registration request (86) to the agent (PDSN 16).Mobile WCD 12 receives the IPv4 address with the registration reply(90), assigns the IPv4 lease time (92), and then communicates via theIPv4 stack (94). In particular, upon assignment of the IPv4 address,mobile WCD 12 is capable of communicating via the IPv4 stack or the IPv6stack. When the IPv4 lease expires (96), or the IPv4 communication isterminated (98), mobile WCD 12 releases the IPv4 address (98), and thencommunicates via the IPv6 stack only (80).

[0043] Various embodiments have been described, primarily in the contextof wireless communication network. However, some embodiments may involveapplication of the techniques described herein to wired devices. Theseand other embodiments are within the scope of the following claims.

1. A mobile wireless communication device that automatically uses afirst address corresponding to a first network communication protocolupon commencement of a communication session, and selectively obtains asecond address corresponding to a second network communication protocolwhen communication with a network resource that communicates accordingto the second network protocol is necessary.
 2. The device of claim 1,wherein the first address is an Internet Protocol version 6 (IPv6)address, and the second address is an Internet Protocol version 4 (IPv4)address.
 3. The device of claim 2, wherein the device releases the IPv4address upon expiration of a period of time that is not equal to aduration of the communication session.
 4. The device of claim 3, whereinthe device tracks the period of time, and releases the IPv4 address uponexpiration of the period of time.
 5. The device of claim 2, wherein thedevice releases the IPv4 address in response to a message from a remotedevice indicating the expiration of the period of time.
 6. The device ofclaim 2, wherein the device releases the IPv4 address in response totermination of the communication with the IPv4 resource.
 7. The deviceof claim 2, wherein the device obtains the IPv4 address by sending anInternet Protocol Control Protocol (IPCP) request from the mobilewireless communication device to a remote device.
 8. The device of claim2, wherein the device obtains the IPv4 address by sending a registrationrequest, and receives the IPv4 address with a registration reply.
 9. Thedevice of claim 2, wherein the device obtains the IPv4 address bysending an Internet Protocol Control Protocol (IPCP) request to a remotedevice.
 10. The device of claim 2, wherein the device obtains the IPv4address automatically upon commencement of a communication session whenIPv6 service is not available.
 11. A method comprising: automaticallyusing a first address corresponding to a first network communicationprotocol for a mobile wireless communication device upon commencement ofa communication session; and selectively obtaining a second addresscorresponding to a second network communication protocol for the mobilewireless communication device when initiating communication with anetwork resource that communicates according to the second networkprotocol.
 12. The method of claim 11, wherein the first address is anInternet Protocol version 6 (IPv6) address, and the second address is anInternet Protocol version 4 (IPv4) address.
 13. The method of claim 12,further comprising releasing the IPv4 address upon expiration of aperiod of time that is not equal to a duration of the communicationsession.
 14. The method of claim 13, further comprising tracking theperiod of time within the mobile wireless communication device, andcausing the mobile wireless communication device to release the IPv4address upon expiration of the period of time.
 15. The method of claim12, further comprising causing the mobile wireless communication deviceto release the IPv4 address in response to a message from a remotedevice indicating the expiration of the period of time.
 16. The methodof claim 11, further comprising releasing the second address in responseto termination of the communication with the network resource.
 17. Themethod of claim 11, wherein the first address is an Internet Protocolversion 6 (IPv6) address, the second address is an Internet Protocolversion 4 (IPv4) address, and obtaining the second address includessending an Internet Protocol Control Protocol version 4 (IPCPv4) requestfrom the mobile wireless communication device to a remote device. 18.The method of claim 11, wherein the first address is an InternetProtocol version 6 (IPv6) address, the second address is an InternetProtocol version 4 (IPv4) address, and obtaining the IPv4 addressincludes sending a registration request and receiving the IPv4 addresswith a registration reply.
 19. The method of claim 11, furthercomprising obtaining the second address automatically upon commencementof a communication session when service corresponding to the firstnetwork communication protocol is not available.
 20. A wirelesscommunication network comprising: one or more first network nodes thatcommunicate according to a first network communication protocol; one ormore second network nodes that communicate according to a second networkcommunication protocol; a packet data service node (PDSN) that providesaddresses corresponding to the second network communication protocol;and a mobile wireless communication device capable of communicatingaccording to the first network communication protocol and the secondnetwork communication protocol, wherein the mobile wirelesscommunication device: automatically uses an address corresponding to thefirst network communication protocol upon commencement of acommunication session, and selectively obtains an address correspondingto the second network communication protocol when communication with anetwork resource that communicates according to the second networkprotocol is necessary.
 21. The wireless communication network of claim20, wherein the first address is an Internet Protocol version 6 (IPv6)address, and the second address is an Internet Protocol version 4 (IPv4)address.
 22. The wireless communication network of claim 21, wherein themobile wireless communication device releases the IPv4 address uponexpiration of a period of time that is not equal to a duration of thecommunication session.
 23. The wireless communication network of claim21, wherein the mobile wireless communication device tracks the periodof time, and releases the IPv4 address upon expiration of the period oftime.
 24. The wireless communication network of claim 21, wherein themobile wireless communication device releases the IPv4 address inresponse to a message from the PDSN indicating the expiration of theperiod of time.
 25. The wireless communication network of claim 21,wherein mobile wireless communication device obtains the IPv4 address bysending an Internet Protocol Control Protocol version 4 (IPCPv4) requestto the PDSN.
 26. The wireless communication network of claim 21, whereinthe mobile wireless communication device obtains the IPv4 address bysending a registration request to the PDSN, and receiving the IPv4address with a registration reply from the PDSN.
 27. The wirelesscommunication network of claim 21, wherein the mobile wirelesscommunication device obtains the IPv4 address automatically uponcommencement of a communication session when IPv6 service is notavailable.
 28. A computer-readable medium comprising instructions tocause a processor to: automatically use a first address corresponding toa first network communication protocol for a mobile wirelesscommunication device upon commencement of a communication session; andselectively obtain a second address corresponding to a second networkcommunication protocol for the mobile wireless communication device whencommunication with a network resource that communicates according to thesecond network protocol is necessary.
 29. The computer-readable mediumof claim 28, wherein the first address is an Internet Protocol version 6(IPv6) address, and the second address is an Internet Protocol version 4(IPv4) address.
 30. The computer-readable medium of claim 29, whereinthe instructions cause the processor to release the IPv4 address uponexpiration of a period of time that is not equal to a duration of thecommunication session.
 31. The computer-readable medium of claim 29,wherein the instructions cause the processor to track the period of timewithin the mobile wireless communication device, and cause the processorto release the IPv4 address upon expiration of the period of time. 32.The computer-readable medium of claim 29, wherein the instructions causethe processor to release the IPv4 address in response to a message froma remote device indicating the expiration of the period of time.
 33. Thecomputer-readable medium of claim 29, wherein the instructions cause theprocessor to release the IPv4 address in response to termination of thecommunication with the IPv4 resource.
 34. The computer-readable mediumof claim 29, wherein the instructions cause the processor to obtain theIPv4 address by sending an Internet Protocol Control Protocol version 4(IPCPv4) request from the mobile wireless communication device to aremote device.
 35. The computer-readable medium of claim 29, wherein theinstructions cause the processor to obtain the IPv4 address by sending aregistration request and receiving the IPv4 address with a registrationreply.
 36. The computer-readable medium of claim 29, wherein theinstructions cause the processor to obtain the IPv4 addressautomatically upon commencement of a communication session when IPv6service is not available.
 37. A method comprising: automatically using afirst address corresponding to a first network communication protocolfor a network communication device upon commencement of a communicationsession; and selectively obtaining a second address corresponding to asecond network communication protocol for the network communicationdevice when initiating communication with a network resource thatcommunicates according to the second network protocol.
 38. The method ofclaim 37, wherein the first address is an Internet Protocol version 6(IPv6) address, and the second address is an Internet Protocol version 4(IPv4) address.
 39. The method of claim 38, wherein the first address isan Internet Protocol version 6 (IPv6) address, the second address is anInternet Protocol version 4 (IPv4) address, and obtaining the secondaddress includes sending an Internet Protocol Control Protocol version 4(IPCPv4) request from the mobile wireless communication device to aremote device.
 40. The method of claim 38, wherein the first address isan Internet Protocol version 6 (IPv6) address, the second address is anInternet Protocol version 4 (IPv4) address, and obtaining the IPv4address includes sending a registration request and receiving the IPv4address with a registration reply.
 41. A network communication devicethat automatically uses a first address corresponding to a first networkcommunication protocol upon commencement of a communication session, andselectively obtains a second address corresponding to a second networkcommunication protocol when communication with a network resource thatcommunicates according to the second network protocol is necessary. 42.The device of claim 41, wherein the first address is an InternetProtocol version 6 (IPv6) address, and the second address is an InternetProtocol version 4 (IPv4) address.
 43. The device of claim 42, whereinthe device obtains the IPv4 address by sending an Internet ProtocolControl Protocol (IPCP) request from the mobile wireless communicationdevice to a remote device.
 44. The device of claim 42, wherein thedevice obtains the IPv4 address by sending a registration request, andreceives the IPv4 address with a registration reply.
 45. A communicationnetwork comprising: one or more first network nodes that communicateaccording to a first network communication protocol; one or more secondnetwork nodes that communicate according to a second networkcommunication protocol; means for providing addresses corresponding tothe second network communication protocol; and a network communicationdevice capable of communicating according to the first networkcommunication protocol and the second network communication protocol,wherein the network communication device: automatically uses an addresscorresponding to the first network communication protocol uponcommencement of a communication session, and selectively obtains anaddress corresponding to the second network communication protocol whencommunication with a network resource that communicates according to thesecond network protocol is necessary.
 46. The wireless communicationnetwork of claim 45, wherein the first address is an Internet Protocolversion 6 (IPv6) address, and the second address is an Internet Protocolversion 4 (IPv4) address.
 47. A computer-readable medium comprisinginstructions to cause a processor to: automatically use a first addresscorresponding to a first network communication protocol for a networkcommunication device upon commencement of a communication session; andselectively obtain a second address corresponding to a second networkcommunication protocol for the network communication device whencommunication with a network resource that communicates according to thesecond network protocol is necessary.
 48. The computer-readable mediumof claim 47, wherein the first address is an Internet Protocol version 6(IPv6) address, and the second address is an Internet Protocol version 4(IPv4) address.